Some of the UK's leading music festivals have joined a ban on "legal highs" being sold at their events and will take part in a "digital blackout" to highlight the danger of the controversial stimulants.

The social media accounts of 24 festivals, including T in the Park, Bestival and Lovebox, will go dark for a day from 9am on Monday, while their websites will show only a grey light bulb on a black window with the message: "Don't be in the Dark about Legal Highs."

Bestival in the Isle of Wight is among the festivals taking part in the digital blackout warning about legal highs. Credit: David Jensen/EMPICS Entertainment

The number of deaths associated with the novel psychoactive substances - better known as legal highs - rose from 10 in 2009 to 68 in 2012, a recent substance abuse report found.

Home Office minister Norman Baker has warned that authorities are in a "race with chemists" in India and China who generate new legal highs on a weekly basis.

Fatboy Slim has been announced as the final headliner for Bestival's 10th anniversary event.

The 49-year-old joins other headliners Elton John and Snoop Dogg in signing up for the five-day festival held on the Isle of Wight in September.

The Praise You star, who will perform the set 'Fatboy Slim's Bestival Birthday Bash', said: "It was at Glastonbury 2003, where I closed the Sunday Best stage for Rob da Bank (Event organiser and Radio 1 DJ) , that I first saw the glint in his eye to create his own festival.

Fatboy Slim performs during the Closing Ceremony of the London 2012 Olympic Games Credit: Michael Kappeler/Press Association Images

"Here I am again, throwing them the biggest birthday bash possible and sharing the main stage alongside Elton John and Snoop Dogg. It's an absolute honour to return for this momentous occasion, staying creative and independent in these times. You've come a long way, baby."

MIA, Franz Ferdinand, Flaming Lips, The Knife, Wu-Tang Clan and Carl Cox are among the other acts to perform at the festival which was voted the UK's Best Major Festival last year.

A woman suffered a shock when her boyfriend proposed to her in a message shown on the screen of Bestival's main stage.

Viv Craske pre-recorded the proposal to be shown to his partner Jenny Engvall at the conclusion of the Bat For Lashes set at the festival on the Isle of Wight. Miss Engvall, who bakes cakes for a living, said yes.

General View of the main stage at Bestival 2012. Credit: David Jensen/EMPICS Entertainment

Mr Craske, 38, said: "I wanted to do something special for the proposal. We came to Bestival a couple of years ago and saw Jenny playing with a friend's son and I realised I wanted to have children with her and we now have a son, Jasper who is 20 months.

"As we were coming back to Bestival I felt this was the place to propose as this is the place where we first became a family. I have been nervous all weekend waiting for this. I chose this moment because it was before Sigur Ros who is our favourite band."